Purpose. The aim is to analyze the features of aortic valve allografts decellularized with trypsin solution or a combination of the sodium dodecyl sulfate/deoxycholate solution. Materials and methods. We performed histological, bacteriological and mechanical testing of graft. Results. It was found that after the removal of cellular elements with trypsin the strength of allograft significantly decreased compared with the control group and the samples exposed to detergent treatment. Histological analysis of aortic allograft specimens showed signifi cantly impaired spatial organization of the connective tissue framework of the valve after the enzymatic treatment. Conclusion. Detergent decellularization is the preferred method for obtaining cell-free aortic allografts because it can effectively remove the donor cells and maintain the microstructure and biomechanical properties of the valve graft.
Several experimental studies have recently demonstrated that temporary autonomic block using botulinum toxin (BoNT/A1) might be a novel option for the treatment of atrial fibrillation. However, the assessment of antiarrhythmic properties of BoNT has so far been limited, relying exclusively on vagal stimulation and rapid atrial pacing models. The present study examined the antiarrhythmic effect of specially formulated BoNT/A1-chitosan nanoparticles (BTN) in calcium chloride-, barium chloride- and electrically induced arrhythmia rat models. BTN enhanced the effect of BoNT/A1. Subepicardial injection of BTN resulted in a significant antiarrhythmic effect in investigated rat models. BTN formulation antagonizes arrhythmia induced by the activation of Ca, K and Na channels.
This work is aimed at developing the modification of the surface of medical implants with film materials based on noble metals in order to improve their biological characteristics. Gas-phase transportation methods were proposed to obtain such materials. To determine the effect of the material of the bottom layer of heterometallic structures, Ir, Pt, and PtIr coatings with a thickness of 1.4–1.5 μm were deposited by metal–organic chemical vapor deposition (MOCVD) on Ti6Al4V alloy discs. Two types of antibacterial components, namely, gold nanoparticles (AuNPs) and discontinuous Ag coatings, were deposited on the surface of these coatings. AuNPs (11–14 nm) were deposited by a pulsed MOCVD method, while Ag films (35–40 nm in thickness) were obtained by physical vapor deposition (PVD). The cytotoxic (24 h and 48 h, toward peripheral blood mononuclear cells (PBMCs)) and antibacterial (24 h) properties of monophase (Ag, Ir, Pt, and PtIr) and heterophase (Ag/Pt, Ag/Ir, Ag/PtIr, Au/Pt, Au/Ir, and Au/PtIr) film materials deposited on Ti-alloy samples were studied in vitro and compared with those of uncoated Ti-alloy samples. Studies of the cytokine production by PBMCs in response to incubation of the samples for 24 and 48 h and histological studies at 1 and 3 months after subcutaneous implantation in rats were also performed. Despite the comparable thickness of the fibrous capsule after 3 months, a faster completion of the active phase of encapsulation was observed for the coated implants compared to the Ti alloy analogs. For the Ag-containing samples, growth inhibition of S. epidermidis, S. aureus, Str. pyogenes, P. aeruginosa, and Ent. faecium was observed.
Objective. The study focused on the production and evaluation of small-diameter vascular grafts (less than 6 mm) by using an electrospinning approach. Methods. The protocols of vascular grafts (VG) to be produced from the solutions of synthetic polymers and their blends with gelatin including those with a semipermeable inner layer were developed. The comparative study of the grafts in vitro and in vivo was carried out. The resistance of VG to displacement, suture retention, layers snagging and compatibility with native artery walls were studied. Also assessed was the time of hemostasis when implanting the grafts consisting of various mixes of polymers, as well as their biocompatibility at different stages of observation. Results. VG produced by electrospinning and containing a semipermeable inner layer possess satisfactory mechanical properties, such as suture retention, resistance to displacement, stability during long term pulsatile stress, do not snag during implantation and form a tight contact with native artery walls. A histological study demonstrates active remodeling of VG including the growth of inner structure typical of a vessel, medium collagen/elastin layer with smooth muscle cells and synthetic fibers and an outer connective tissue capsule without any signature of inflammation. An immunohistochemical study demonstrates more efficient accumulation of smooth muscle cells in VG produced from polycaprolactone (PCL) as compared to other VG tested. VG produced from the PCL-gelatin blend and containing an inner semipermeable layer, as well as similar VG containing polylactic-co-glycolic acid (PLGA) in the inner semipermeable layer tended to produce an endothelial inner layer faster as compared to VG from PCL. However, VG with PLGA acid had a tendency to loose endothelial cells, possibly due to PLGA degradation. VG produced from PCL-gelatin blend and containing the inner semipermeable layer demonstrate limited accumulation of smooth muscle cells and progressive settlement with endothelial cells. Conclusion. A comparative study of different VG produced by electrospinning enables to select variants of polymeric composition and structure of the implant that provide the best bio- and hemocompatibility. VG produced by electrospinning from PCL-gelatin blend and supplied with a semipermeable layer can be recommended for subsequent clinical approbation.
The Ross procedure has emerged as an attractive option for aortic valve replacement in children and young adults. This work represents immediate postoperative period results and long term outcome after Ross procedure among the pediatric population in the single center experience. The main part of a material is submitted by the statistical analysis of risk factors in the early postoperative period within more than 5 years postoperative analysis of long term condition.
Background. In recent years, transcatheter implantation of the aortic valve has become increasingly performed as an alternative to "open" prosthetics. The undoubted advantage of this technology is its minimally invasive nature, which in most cases provides a favorable clinical outcome of the intervention. The transcatheter method of aortic valve prosthetics does not require sternotomy and connection of an artificial circulation device, which significantly reduces the risk of postoperative mortality and complications. However, despite all the advantages of the existing models, they are not without drawbacks that force researchers to develop and test new transcatheter valves. The problem of experimental studies of new models of self-opening transcatheter aortic valves is mainly determined by the anatomical features of the aortic root of animals. In this regard, the development of a reliable method of implantation of valve prostheses in the experiment is an urgent problem of preclinical testing.Aim. Development of a protocol for open implantation of a transcatheter aortic valve in experiment and evaluation of long-term results.Methods. To develop an experimental model, pigs of the "Landras" breed, females weighing 129.83 ± 9 kg were used. Transcatheter aortic valve implantation was performed under conditions of artificial circulation and moderate hypothermia (33-34°C) through a transverse aortotomy under the control of vision. During the experiment, invasive monitoring of blood pressure, central venous pressure, heart rhythm, body temperature, blood gas composition, activated clotting time was performed. The correct positioning and hemodynamic parameters after implantation were evaluated using transesophageal echocardiography.Results. In a series of chronic experiments, 18 open implantations of self-opening transcatheter aortic valves were performed. Successful positioning was achieved in 100% of cases. The developed protocol of open implantation made it possible to achieve reliable fixation of the prosthesis in the orthotopic position, as well as to prevent the migration of the prosthesis, the development of mitral regurgitation, paraaortic fistulas and coronary circulation disorders.Conclusion. In the course of the study, a simple and effective method of open implantation of a transcatheter aortic heart valve prosthesis was developed in an experiment. Received 1 October 2021. Revised 1 November 2021. Accepted 12 November 2021. Funding: This work was carried out within the framework of the state task of Ministry of Health of Russian Federation No. 121032300337-5. Conflict of interest: Authors declare no conflict of interest. Contribution of the authorsConception and study design: M.O. Zhulkov, D.A. Sirota, K.V. Kozyr, D.S. SergeevichevData collection and analysis: M.O. ZhulkovDrafting the article: M.O. ZhulkovCritical revision of the article: D.A. Sirota, A.M. ChernyavskiyExperimental part: M.O. Zhulkov, H.A. Agaeva, A.K. Sabetov, I.S. Zykov, A.R. TarkovaFinal approval of the version to be published: M.O. Zhulkov, K.V. Kozyr, I.S. Zykov, A.R. Tarkova, H.A. Agaeva, A.K. Sabetov, D.A. Sirota, D.S. Sergeevichev, A.M. Chernyavski
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